Embodiments of the present invention relate to touch screen devices. More specifically, the present invention relates to touch screen devices capable of sensing the force of a touch and methods of use thereof.
The use of touch screen devices and touch user interfaces are now quite common place for consumers: from the signature machine in the checkout isle, to automatic teller machines at banks, to ticketing kiosks at airports, and the like. Touch screen capability is also now quite common in hand-held devices: from the Palm Pilot, to the Google Nexus One, to the Apple iPad, and the like.
Touch capability has typically been enabled for many touch screen devices through the incorporation and use of a resistive sensor network. These sensor networks can sense when a single finger of the user touches the display, or uses a stylus to touch the display.
Drawbacks to touch screen devices incorporating resistive-based sensors determined by the inventor include that if a user inadvertently touches two locations on the touch screen at the same time, the location reported by the touch screen if often incorrect. As such devices typically only support detecting one finger at a time, for example, the reported touch location may be between the two fingers. Another drawback includes that the user has to press down with some force on the touch screen before the touch screen can detect the user touch.
Newer capacitive-based touch screen displays are now more commonly used and address some of the short comings of a resistive-based sensor network. As an example, capacitive-based touch screens can sense the individual locations of fingers when the user touch the display with more than one finger. Accordingly, these devices are often termed “multi-touch” displays. As another example, capacitive-based touch screens do not require the user to press-down upon the touch screen before the finger is sensed.
Drawbacks to the use of capacitive-based touch screens determined by the inventor include that even if a user inadvertently brushes her finger across the touch screen, that accidental swipe may still be sensed as a user input. This is particularly frustrating, for example, when a user is trying to touch-type using a virtual keyboard to input text. In such cases, as the user hovers his fingers over the home row of the virtual keyboard, often his little finger, middle finger, or the like may accidentally touch the surface of the display. These touches are then incorrectly sensed as presses of the virtual keys causing typographical errors.
Although many touch screen devices include automatic spelling/prediction software to attempt to reduce the effect of typographic errors, in many instances, the predicted word is not the word the user wants. Accordingly, the user must constantly watch the touch screen display to monitor the automatic predictions and to select the correct word. These types of interruptions greatly interfere with the text-entry efficiency provided by the user's ability to touch-type.
Additional drawbacks determined by the inventor of resistive and capacitive based touch screen include that the sensed touches are typically binary in nature, i.e. either the finger is not touching or the finger is touching. These types of devices cannot sense the force with which a user touches the touch screen display. From a user point of view, these touch screen devices also do not provide a user with any sensation of pressing a button or key, i.e. they provide no tactile feedback.
One type of touch screen display used by Research In Motion (RIM) to provide the user with tactile feedback was used in the Blackberry Storm series of devices. In these products, one or more micro sensors were placed under the capacitive-based touch screen display. In operation, when the user wanted to make an on-screen selection, the user would press the touch screen display. The touch screen display would then deflect (by about a millimeter) and cause one of the micro sensors to physically click or switch. The physical click would thus provide the user with tactile confirmation of the button press.
Drawbacks to such approaches determined by the inventor, include that such devices were limited to the physical performance of the micro sensors. For example, a user could not type very quickly with such an approach because the user had to pause between key presses to wait until the micro sensors could fully reset before she could press the next key. Further, if the user placed two or more fingers on the touch screen at the same time she depressed the touch screen (activating the micro sensor(s)), it would be unclear which touch screen location or finger the user intended.
From the above, it is desired to have a multi-touch touch screen display without the drawbacks described above.